1. Field of the Invention
This invention relates to document handling apparatus and methods adapted for recirculating of original documents between storage bins and a processing station. More particularly, the present invention relates to apparatus and methods for automatically producing multiple copies of a set of original documents. The present invention is particularly well suited for use in copier/duplicator devices capable of producing exact copies of original documents.
2. Description of the Prior Art
In using the earlier copier/duplicator devices and some contemporary office copiers, the operator can only run multiple copies of a single document or stack of documents by recycling the copying machine for each copy required. This procedure may be acceptable where a small number of documents are to be copied multiple times or where the output of the copying machine includes an automatic collator apparatus for redistributing multiple sequential copies of each page. In an effort to reduce extensive operator attention to the machine operation, various devices have been developed to automate multiple copy runs of original documents with minimal operator intervention. Further, attempts have been made to render the copier/duplicator machine independent of external or additional collator apparatus by recirculating original documents within the machine itself so that multiple collated sets are produced.
For instance, one arrangement includes a cassette which is preloaded with a stack of documents to be copied and with an intervening spacer bar resting on the top of the document stack so that the documents can be bottom fed from this cassette to a processing station and returned for top stacking in the cassette. Such apparatus is incapable of accepting more than one duplicating job at a time within the cassette and further requires the hazarding of paper jam difficulties associated with actuation and removal of the separator bar each time a complete set of documents has been copied.
In yet another form of prior art device with a recirculating document capability, two document receiving stations or bins are placed on opposite sides of a copying station with the documents being bottom fed from one receptacle, across the processing station and top fed into the opposite receptacle. The device requires the reversal of these functions with appropriate gating for bottom feeding from the second receptacle and top stacking into the original receptacle. As with the cassette loaded recirculating structure mentioned previously, this shuttling apparatus can accept no more than a single copying stack at a time. The machine operation must be interrupted while the operator reloads the input tray for each job that must be run. Further, none of the known prior art recirculating techniques are capable of error or jam recovery which require the return of the last document passed through the processing station for a repeat processing at that station.